Hypsometer



i W/TgESSEs May 15, 1923.

1 yl. v 17 2.

R. G. MERRITT HYPSOMETER Filed Feb. 11, 1915 2 Sheets-Sheet 1 IN VEN TOR R. G. MERRITT Filed Feb. '11, 1915 2 Sheets-Sheet 2 A have ,lcueL.

Oil/161 6 Below ,ZeoeL.

l/VVENTOR M foz/w x 7 Allarney Patented May 15, 1923.

umrso STATES ROBERT G. MERRITT, or NEW roman. Y.

f 19455347 PAT EN F m E HYPSOMETEB.

Application filed. February 11, 1913. Serial No; 747,755. I

(FILED UNDER THE ACT OF MARCH 3, 18 83, '22 STATJL, 625.),

employees in the prosecution of work for theUnited States, or by any person in the United States, without the payment of any royalty thereon. g

1 This invention relatesto hypsometers, and more particularly to hypsometers for use in determining the number of log lengths in any standingtree.

. All the commonlyused instruments-for making such calculations are of delicate construction, necessitating *care in their handling and moreover they are expensive.

The instrument of the present invention is constructed in the form of a stick, similar in appearance to an ordinary yard stick,

' having upon one of its sides graduations spaced at the same predetermined distance apart; and this distance is equal to the product of the predetermined log length and the perpendicular distance atwhich the instrumentis held from the eye of the 0bserver, divided by the perpendicular distance at which the observer stands from the tree. The instrument is graduatedto be used at a certain distance from the observers eye when the observer is standing at 40 a certain distance from the tree. As these two distances vary, the distance between graduations on the hypsometer must be varied. i r

If a stickhas graduations for use at only one-set of distances this is indicated on the edge of the stick- Y It is obvious that the stick may be used for ascertaining the height of objects as f well as the number of log lengths in trees.

In the accompanying-drawings illustrating the invention, in the several figures of which like parts are similarly designated, Figure. 1 is'a side view of a hypsometerconstructed in: accordance with :my invention and adapted for use at a single distance only from the tree or other object tobe measured. Fig, 2 1s an edge View. Fig. 3 is a view showing the manner in which the instruat."

ment is used; Fig. 4 shows adevice for determining the correct distance at which to hold the instrument from the eye of the observer, the use of which is illustrated'in Fig. 3. Fig. 5 is a diagrammatic view illustrating the geometrical principle on which the instrument is constructed.

1 is the stick, having'graduations 1, 2, '3, tand 5, the distance between such graduations being determined as will be hereinafter'describedr I It has been ascertained, by experiment, that the average reach of a man is twentyfive inches, and that the most advantageous distance for the observer to stand from the 1 object or tree to be measuredis' sixty six feet, which two-distances will be assumed to govern the following discussion. In using a stick graduated to conform with these two distances, or for others,it is-desirable that the observer should know that heis holding the instrument at the proper distance from him, and for this purpose, I provide the ring 2 of suitable diameter to easily slip along the stick, and to this ring. I- attach anon-elastic andnon-shrinkable cord'3. At the far end of this cord, if the stick is for a man With a twenty-five inch reach, I makea knot 4, the knot being so situated that when the cord 3 is drawn taut, the distance from the face of the stick to the knot will be twenty-five inches.- Therefore, if the observer wishes to use the stick he can-readily ascertain the correct distance at which to hold it from his eye by inserting the stick through the ring, holding the knot near his.eye,pand drawing the string taut as shown in Fig. 3. The distance atwhich the instrument isto beheld from the eye of the observer, is indicated infigures on one edge of the instrument as shown at 7.'

The stick 1 is provided with a ferrule 5 at each end, and at one end the ferrule 5 and stick 1 are piercedbya hole 6 through which a thong or cord may be run for suspending the stick from the shoulder of the user when it is being carried. 1 i

This hypsometer isfequally well adapted for use when the observer stands above, on

a level with, or below the base of the butt log of a tree or the-base of the object to be measured, as is illustrated in Fig. 5-". If the tree or other object to be measured is inclined, the instrument should, be given a like inclination so that the object and instrument will be parallel.

F or purposes of describing the geometrical principle of'the device; and referring to Fig. 5, let the graduations 1, 2, 3, 4, and 5' on the hypsometer be designated by 0, d, 6-,

r f, and g respectively,-and the lower end of the stick be designated b and the point of observation bedesignated A; and the log DE; EF and FG;

Using for demonstration the case in which the point of observation is on a level with the b'a-se of the butt log of thetree, or with the base of the object'to be measured, the proof'of the'factthat the graduations on the stick are all the same distance apart, is as follows r The distances AB, 136 and BC, CD, DE, 'EF and FGr are known. The tri- -angle's;ABO and A60 are similar; because their angles are equal. Therefordvthe altitude BO of the large triangle is to the altitude 60 of'the small triangle as the hypdte nuseAC of the large triangle is tothe hypotenuse A0 of the smalltriangle. Also the triangles AQD' and are similar, therefore CD isto ed as AC is to A'c; butthings which equal the same thing are equal to eacliother, therefore, BC isto 7J0 as CD is to 0d. But BC is equal to CD, hence be is equal toad! be is also equal to 4%, cf and fg, severally, as can be similarly proved.-

The formula, hereinbefore stated; by which thestick is graduated, viz; the distance between graduations' is equal to the product of-the unit of length and the perpendicular distance from the point of observation to the stick, divided by the persimilar pendiculan distance from the point of observation to the object to be measured, applies for all1pO S1tl0IlS of the observer above, on a level with, or below the level of the base of the object to be measured,'and the proof thereof is as follows :--In the case where the point ofobservation above the level of the base of the object to be measured:- a

The triangles "AB" E and Alf'e are and the triangles AEE and Aef are similar In thecasewhere the point oi observation lengths on thejtree be designated BC, CD

is on a level with, the base the obj ect to 1 be measured i The triangles ABC and Abe are similar 7 ;".BC; bc::AB:.-Ab

b BO v c B In the case wherethe point ofobservation is below the level ofthe base of the object to be measuredz-e-b The triangles ABC and A130 aresirnilar V to handle; cannot become inaccuratebecause w. -v 1v. m of changing atmospheric cond1t1ons or rough handling,

construction? For careful measurement of individual trees on sample plots, or; wherever great precision is more important thanlspee'dbr convenience this hypsometer; is not an-f en. tirely satisfactory substitute for, the wellknown Faustmalin height measure, or some i of the other'delicate and expensive instru This ,hypsoineter convenient-and; 1 i

n r ehean and-a ee ments; but ior ordinary itimberestimating it far surpasses these instrumentslbecause of its lightness, simplicity; ease ofmanipuflation, indestructibility and the ease"with which calculations may be 'made witli This instrument may be presides on one side with the data of the wen-immanen more sticklan d it then" constitutes a com bined vcaliper and hyps'ometer, thusdoing away with the necessity. for carryingbotli calipers and hypsometers in thef fi'eld. *I'f' desirable, the well-known Scribner decimal G'ruledata'may be placed upon an edge of the instrument, thus"making a convenient,

practical and efli cient instru'ment fori around woods use. J

This hypsometer may be graduated either I for use at a single specified distance from the tree, or for use at se'veral differentidistances from the tree, in which latter ca'sefthe dif ferent 'sets'of graduations' would" -have'fa designation of the distance from the" which they become effective.

It is to be understood that I do not limit my invention to the particular-r type atstiek shown in the drawings, asfit is obvious that it may be of any convenient shapeor fo'rni, 1

to marl; the graduations'.

-What'I claim"is:+-f a A hypsometer,-comprising a stick ada t-' ed for use in; a yer-tical position and having marked upon "it g raduationsg-the' between twe of is 1211 a so long as it has sufficient length' 'onwhieh ease; a

a device for determining the proper distance at Which the instrument is to be held from the observer When in use, comprising a ring to be slipped over the stick and a cord attached at one end to said ring and having a knot at a predetermined distance from its other end.

In testimony whereof I have hereunto'set my hand this 10th day of February, A. D. p

1913. y I i.

ROBERT G. MERRITT. Witnesses:- 1.

H. G SPAHR, A. P. HAIILTON. 

